Manufacture of steel.



No. 723,501. PATENTED MAR. 24, 1903.

H. G. 0. THOFEHRN. MANUFAOTURE 01-" STEEL.

APPLICATION FILED DEC. 17, 1902.

N0 MODEL. 2 SHEETSSHEET l.

FIG--2- \NVE'NTQR ATTORNEYS PATENTED MAR. 24, 1903.

H. G. G. THOFEHRN. MANUFACTURE OF STEEL.

APPLICATION FILED DEC. 17, 1902.

2 SHEETS-SHEET 2..

I0 MODEL.

Wn-Naaaas INVBNTOR UNITED STATES FFICE.

PATENT MANUFACTURE OF STEEL SPECIFICATION forming part of Letters Patent N 0. 723,501 dated March 24, 1903. Application filed December 17, 1902. Serial No. 135,609. (No model) the zone of action of the blast-pipes-that is To all whom it may concern:

Be it known that I, HERMANN GEORGES CHRISTIAN THOFEHRN, civil engineer, a citizen of the United States of America. and a resident of No. 350 Rue St. Honor, Paris, in the Republic of France, have invented certain new and useful Improvements in the Manufacture of Steel, of which thefollowing is a specification.

This invention relates -to important improvements in the manufacture of steel, consisting in melting cast-iron or pouring it already melted in a hearth-furnace, such as a Martin furnace or the like, and in blowing onto thesurface of the metallic bath by means of blast-pipes distributed around the furnace according to directions tangential with a circle having its center about in the middle of the melted mass a mixture of air, steam, lime reduced into grains, and hydrocarbons. The presence of the hydrocarbons produces on the surface of the bath in the zone where the blowing is effected a considerable increase of heat, so that the chemical reactions which are necessary for the treatment are produced rapidly and thoroughly, and the temperature is, besides, increased to a degree which is sufiicient to maintain the mass liquid during the formation of the steel, which would be impossible to obtain in such a treatment without said hydrocarbons. The reactions obtained by the compound jet are a strong oxi dation of the bath, resulting from the presence of steam and air, which produces, with the carbon, sulfur, and arsenic, the formation of volatile products, which escape, and which produces at the same time, with the other substances to be eliminated, such as silica and phosphorus, oxide which by getting combined to the lime blown in forms a slag which floats on the bath. At the same time the mechanical effect of the blast-pipe jets produces a whirling on the surface of the bath about in the middle of the furnace, which drives the slag formed away from the zone of action of said blast-pipes, so that this slag forms a layer on the outer surface of the bath, which protects it from the contact of the heating-gases coming from the hearth. The slag which accumulates against the walls of the furnace protects at the same time said walls against corrosion. On the contrary, in

to say, about in the middle of the molten baththe jets act constantly on fresh parts of the mass to be treated and produce very rapidly simultaneous oxidation and scorifioatio'n on account of the high temperature and without it being possible that the products resulting from these reactions mix with the remainingmass of the bath. The slag is drawn awayatsuitable intervals by the working doors of the furnace.

The accompanying drawings show as an example a hearth furnace arranged for car rying out my treatment.

Figure 1 is a vertical section of the furnace. Fig. 2 is a sectional plan view. Fig. 3 is a partial elevation view of the hopper in which the granulated lime is placed and of the blast-pipe. Fig. 4 is a plan view, partially broken away, of the two blast-pipes coupled.

The furnace illustrated in'the drawings is an ordinary gas-furnace, in which special arrangements have been provided allowing to carry out the new manufacture. The steam arrives through the pipes (1,, passes through the coiled pipes 1), arranged in the regenerating-chain bers of the furnace, and passes from there by flexible tubes (1 to the blast-pipes 6. These blast-pipes, Figs. 3 and 4, can be more or less opened by means of a socket or sleeve f, provided with orifices for regulating the quantity of air to be driven into the furnace. The quantity of steam admitted is regulated by the valve g, and the quaiitity of hydrocarbon which may flow through the hollow rod of said valve is regulated by a cock 7", placed on the conduit which connects the valve with the reservoir. The lime in a suitable state of division is placed in a hopper or box h, bolted, for instance, on the T'irons of the vertical uprights serving to secure the furnace. This hopper terminates in a tube 1', which extends vertically and quite close to the air-inlet orifices of the blast-pipe. A damperj, placed in the tub'et' and provided with a longitudinal aperture, permits of regulating the quantity of lime which falls through the tube and which is sucked by the blowing in of steam through the orifices of the blast-pipe.

The blast-pipes may rest outside the furnace on metal rods 70, arranged on the T-irons the same inclination.

of the furnace, and inside on fire-bricks Z. [On lowering the rods k and removing the "bricks the position of the blast-pipes can be varied as to height, at the same time keeping The ends of the blastpipes which are subjected to the-action of the heat of the furnace are easily removable by means of bayonet-joints, as shown in Figs. 3 and 4.

For a treatment as above described a neutral or, preferably, basic lining is employed or also a lining of very pure chrome minerals or any other lining adapted to this kind of work. 7

The object of the treatment is to diminish the proportion of carbon in the metallic bath and to eliminate the impurities, which are generally silicon, a small quantity of sulfur, arsenic, phosphorus, and the like. It is preferable to operate with considerable quantities, (thirty to one hundred tons at a time,) so as to have time to examine the samples removed without interrupting the treatment, which is rapid. 'lhistreatmentis rather deliessary to maintain it within very narrow limits. Great attention 'must be paid to the formation of the protective layer of slag. As to cate, the quantity of carbon remaining in the bath being somewhat small and it being necthe blowing in of hydrocarbons, it enables me to obtain a very high temperature necessary for the reactions and for keeping the mass in a fluid state.

Having now described my' invention, what I claim as new, and desire to secure by Letters Patent,- is

1. A process for'the manufacture of steel consisting in blowing in a hearth-furnace, on the surface of a cast-iron bath and by means of blast-pipes, a mixture of air, steam, lime and hydrocarbons, substantially as and for the purpose set forth.

2. A process for the manufacture of steel consisting in blowing in a'hearth-furnace, on the surface of a cast-iron bath and by means of blast-pipes arranged around the furnace according to the direction tangential with a circle having its center about in the middle of the melted'mass, a mixture of air, steam, lime and hydrocarbons, substantiallyas and for the purpose set forth.

, In witness whereof I have hereunto set my hand in presence of two witnesses.

llERlllANN GEORGES CHRISTIAN 'lllOl EllRN.

Witnesses;

' LOUIS MosEs, EDWARD P. MACLEAN. 

